Conventionally, a hot-press forming is publicly known in which, after heating a workpiece, such as a steel plate, to above a temperature at which an austenite structure appears therein, cooled dies press and quench the workpiece at the same time.
In the above-mentioned hot-press forming, electric heating is widely known as a technique for heating the workpiece (for example, see Patent Literature 1).
The electric heating is a technique for heating the workpiece by utilizing Joule heat generated by applying an electric current to the workpiece with at least one pair of electrodes attached to the workpiece.
In the electric heating, the heated workpiece thermally expands, and deforms. Therefore, it is necessary to control the deformation of the workpiece to a minimum by bringing the electrodes into contact with the workpiece at a predetermined pressure to fix the workpiece.
However, the electrode used for the electric heating abrades by friction and the like because the electrode comes in contact with the workpiece at such a high pressure as to control the deformation of the workpiece to a minimum as mentioned above. When the electrode abrades, the abraded part of the electrode does not closely come in contact with the workpiece, which makes it impossible to uniformly apply an electric current to the workpiece. Moreover, the abraded part of the electrode, namely, the part of the electrode which does not closely come in contact with the workpiece sparks, which may cause problem that the electrode melts and chips for example.